The present invention generally relates to image recognition methods and apparatus. More specifically, the invention relates to methods and apparatus for identifying, extracting, and interpreting a portion of the image prior to detailed image processing/recognition processing.
The United States Postal Service has rights in this invention pursuant to Contract No. 104230-88-0-2943.
Humans have the ability to process visual images at a relatively instantaneous rate. Once an image is captured, the human brain quickly and virtually instantaneously interprets the entire image, as well as portions thereof. Humans are able to virtually instantaneously decipher useful information in the image despite the presence of "noise, . , " i.e. irrelevant information. For example, one can virtually, instantaneously recognize a printed word in an image despite degradation due to background clutter.
There has been much research over the years regarding the configuration of machines, most notably computers and electronic devices, to perform image recognition processing at a rate approaching and enjoyed by humans, or faster. Such a rate as referred to as real-time processing. However, the task has proven difficult. The simple process of identifying differences between two objects or pieces of information can take millions of calculations and require relatively long periods of time. Thus, many real-time processing applications, time is not available to perform detailed image processing over an entire image.
In an effort to enhance mail delivery and to accommodate the ever increasing volume of mail delivered in the United States, the United States Postal Service (USPS) developed a bar code (hereinafter referred to as the "POSTNET" bar code, "POSTNET" being an acronym derived from Post Numeric Encoding technique) for use on mail that would be applied both by the USPS and its customers. The idea was to provide a code that could be quickly recognized and interpreted by a machine.
The POSTNET bar code comprises a series of tall and short bars, and has thus far been placed in the lower right-hand corner of an envelope or card. To accommodate the maximum types of printing technologies, a visible code was selected. Internal to the USPS, the code generally is applied using ink jet printing devices. Most mailers have printed the bar code using offset printing at the time a batch of reply mail pieces is printed. Bar code readers play a significant part in the automation process used by the USPS. Present readers have limitations imposed on them by earlier designs and by the characteristics of the bar coded mail pieces. Presently, the bar code readers use relatively simple techniques for detecting one bar at a time. Further, these readers depend on locating the bar codes at closely pre-defined positions on mail pieces.
Existing operational apparatus and methods are able to detect and read POSTNET bar codes only in a limited, defined clear zone that can have no extraneous printed or background information. Such conditions exist only as desired goals and some letter mail suffers because the bar code is lost in background clutter. These apparatus cannot locate a bar code outside the predescribed area.
The wide variety of pigments and dyes employed in the printing processes to produce an almost infinite advertising copy, printed matters, and other interfering data results in the existing bar code readers rejecting a certain percentage of the mail pieces being processed.
It is, therefore, highly desirable to provide a bar code reader that can effectively identify and interpret a bar code on a piece of mail despite the inclusion of a lot of background "noise," such as graphics printing or alphanumeric printing.
Additionally, it would be helpful to be able to accomplish the foregoing independent of the location of the bar code. This capability will permit any major mailer to print his own USPS bar code at any point on the mailpiece and not be restricted to the current limited acceptable location. The major mailer will receive favorable postal rates by printing the bar code which the USPS has had to do in the past.
In addition to the POSTNET bar code, however, it would also be beneficial to recognize other printed information, such as address block printing so that it also can be extracted from a noisy background and interpreted for letter mail not having bar codes.